Conventionally, industrial robots have been used widely for purposes of taking out transfer objectives from a storage section, which stores the transfer objectives, as well as bringing transfer objectives into the storage section. Known as such industrial robots are those models that are used to take out semiconductor wafers, as transfer objectives, from a vacuum chamber, as a storage section; and meanwhile they also bring semiconductor wafers into the vacuum chamber (Refer to Patent Document 1).
An industrial robot described in Patent Document 1 is built in a semiconductor device manufacturing system. The industrial robot takes out a semiconductor wafer from a load lock chamber (a vacuum chamber), into which the semiconductor wafer is brought externally, and then brings the semiconductor wafer into a processing chamber (another vacuum chamber), where a prescribed processing operation is done on the semiconductor wafer. Meanwhile, the industrial robot is located in a transfer chamber (still another vacuum chamber) around which the load lock chamber and the processing chamber are placed.
In these years, industrial robots are requested to operate at high speed for transferring semiconductor wafers for improvement of productivity. Meanwhile, even in the transfer operation at high speed, it is necessary to grasp a semiconductor wafer surely on a robot hand, on which the semiconductor wafer is placed, so as not to dislocate the semiconductor wafer. Though an industrial robot operating in the atmosphere can commonly apply a method of grasping a semiconductor wafer by vacuum chucking, an industrial robot placed in a vacuum chamber cannot grasp a semiconductor wafer by vacuum chucking. Patent Document 1 proposes a clamping mechanism of a mechanical type for grasping a semiconductor wafer on a robot hand, as a method that satisfies the requirement from the transfer operation at high speed.
The clamping mechanism proposed by Patent Document 1 includes a lever mechanism that contacts the semiconductor wafer on the robot hand, and a working member for operating the lever mechanism mounted on a robot arm that supports the robot hand to keep the robot hand rotatable. Meanwhile the working member is placed at a position being eccentric from the turning center of the robot hand.
The lever mechanism is operated according to a relative turning operation between the robot arm and robot hand. The clamping mechanism proposed by Patent 1 enables grasping and releasing the semiconductor wafer by using the lever mechanism in this way.
[Patent Document 1]
Japanese Unexamined Patent Publication (Kokai) No. JP2000-308988
In these years, semiconductor devices are downsized and thin-profiled. According to downsizing and thin-profiling of the semiconductor devices, semiconductor wafers are also thin-profiled. However, the clamping mechanism for semiconductor wafers proposed by Patent Document 1 is not provided with sufficient consideration for clamping such a thin-profiled wafer. Therefore, the clamping mechanism for semiconductor wafers described in Patent Document 1 is in danger of making a physical impact against a semiconductor wafer when grasping the semiconductor wafer so as to eventually cause damage to the semiconductor wafer.
Furthermore, the clamping mechanism for semiconductor wafers proposed by Patent Document 1 operates the lever mechanism, through the relative turning operation between the robot arm and robot hand, by using the working member that is placed at the position being eccentric from the turning center of the robot hand so as to grasp and release the semiconductor wafer. Consequently, the mechanism for grasping and releasing the semiconductor wafer becomes complicated.